Rubber particles by nature tend to coagulate when left at room temperature. Hence, conventionally, rubber particles are kept at low temperatures to prevent coagulation during storage, transportation and other periods.
However, since enzymes involved in rubber synthesis are not activated at low temperatures, rubber cannot be efficiently synthesized from rubber particles at low temperatures. Accordingly, when natural rubber is synthesized from rubber particles in a test tube (or industrial plant), the temperature of the reaction solution needs to be raised to a temperature (approximately 37° C.) that activates the enzymes.
Rubber particles, which are harvested from the latex of rubber-producing plants, are particles coated with a lipid membrane. Since the membrane is a natural membrane, proteins that have been synthesized in the plants are bound to the surface of the membrane. Known examples of the proteins include rubber elongation factor (REF) and small rubber particle protein (SRPP) (see, for example, Non-Patent Literatures 1 and 2). It is also known that the decrease in the expression of the gene coding for REF in a rubber-producing plant results in a reduced ability to synthesize rubber.
Meanwhile, it is known that rubber synthesis is promoted when rubber particles are present with SRPP expressed in a recombinant microorganism engineered to express SRPP (see, for example, Patent Literature 1).